To provide an overview of the entire technical field, first of all, for example, US 2002/01900162 A1, U.S. Pat. No. 6,765,383 B1 and the publication “A new airborne tandem platform for collocated measurements of microphysical cloud and radiation properties” by W. Frey et al. (in Atmos. Meas. Tech., 2, 147-158, 2009) should be mentioned, which, however, exclusively deal with passive airborne platforms.
From JP 2000-292097 A a towed active airborne platform is known that is used as an aerial target for military training purposes. This airborne platform is cylindrical in design and comprises four axial air guide surfaces that are arranged in front of the middle region so as to be orthogonal relative to each other and that can be considered to be aerofoils, and four axial air guide surfaces in the rear region that are also arranged so as to be orthogonal relative to each other and that are used for flight stabilisation. Only the aerofoils are rotatably arranged on radial axes; they are used for manoeuvring the airborne platform. A similar airborne platform is known from U.S. Pat. No. 4,014,481 A. However, in this design the aerofoils are not rotatably arranged on axes, but instead comprise integrated spoilers that are comparable to control flaps, and by way of torsion bars can be deflected in that electromagnets are excited. If the electromagnets are not excited, said spoilers return to the initial position. However, as a result of cable attachment on the nose of the airborne platform, only extremely limited manoeuvrability of the airborne platform is provided. The spoilers are intended to generate fast, almost jerky, movements of the airborne platform in order to simulate a difficult aerial target. From US 2013/0062464 A1 a towed airborne platform is known which is manoeuvrable by means of various control surface devices. In this arrangement the airborne platform comprises several aerofoils that are arranged in a cruciform shape, box shape or lamellae shape. In this manner stable manoeuvrability is to be achieved. However, such manoeuvrability is again greatly restricted in that the airborne platform is towed and in that the cable is latched to the nose.
The state of the art closest to an embodiment of the invention is known from the presentation “Measurements of Air-Sea Fluxes with a Controlled Towed Vehicle (CTV)” by D. Khelif et al. This presentation was published in the context of the 2010 Ocean Sciences Meetings of the UNOLS Scientific Committee for Oceanographic Aircraft Research in the Town Hall Session in Portland, Oreg., USA, on Feb. 2, 2010; it can be downloaded from the internet (status Nov. 21, 2013) under URL <<http://www.unols.org/meetings/2010/201002sco/201002scoap_09.pdf.>>.
The known CTV is a cylindrical airborne platform (approx. 2.2 m in length, 25 cm in diameter, weighing 40 kg) for the non-contacting determination of measurement data from the airspace. To this effect a carrying cable is latched to the middle region of the airborne platform, and the airborne platform is towed through the air by an aircraft, with the latter being a powered air vehicle. The known airborne platform comprises various sensors for determining the measurement data, for example meteorological sensors (pressure sensor and temperature sensor, hygrometer and anemometer as well as trace gas sensor systems) and for determining the position of the airborne platform in the air, for example radar-supported altimeter, GPS system, navigation system and video camera. No forward-looking sensors for position determination of the airborne platform are provided. In order to supply electrical power to all the on-board electrical components the known airborne platform comprises rechargeable batteries. In the middle region of the airborne platform two short stub-wings or aerofoils are arranged that are rotatable on a radial axis by way of an electrical adjusting device. By way of rotation of the aerofoils a change in altitude of the airborne platform can be effected. If the carrying cable is fully extended, the airborne platform flies in equilibrium at a particular distance from the aircraft, wherein the carrying cable is curved as a result of aerodynamic drag. If in this initial position the aerofoils are rotated, as a result of downthrust the airborne platform can descend still further (while tightening the carrying cable). Thus the flight altitude of the airborne platform can be still further reduced. At a minimum the airborne platform can fly at 10 m above the open ocean, a region without natural obstacles. In the lowered state the airborne platform can climb again in that the aerofoils are rotated in the opposite direction. For constructive flight stabilisation the known airborne platform further comprises several air guide surfaces in its rear region radially arranged on its longitudinal axis, wherein two first air guide surfaces are arranged so as to be parallel to the aerofoils. These air guide surfaces are arranged rigidly and in a non-adjustable manner on the airborne platform. They are not used for changing the flight position. Thus, the CTV is not independently controllable laterally. Furthermore, the known airborne platform comprises a computer-supported control device that has an automatic flight management system for controlling the flight position (flight altitude) of the airborne platform in a self-acting manner. By changing exclusively the flight altitude it is possible to fly over obstacles in a controlled manner, wherein such control is, however, carried out by the operator on board the towing aircraft. If flying over an obstacle is not possible or no longer possible, for the purpose of jettisoning the airborne platform, predetermined braking points are provided in the carrying cable, as are manually-operable cutting devices in the winch region of the aircraft. The flight management system further comprises a malfunction module, which is activated in the case of a malfunction, by means of which malfunction module the adjusting devices of the aerofoils are reset to their initial position so that the airborne platform moves back to its higher flight position in equilibrium. No statement relating to the type of malfunction or the design of the malfunction module is made. It must be assumed that in the case of an emergency the airborne platform is jettisoned, which can result in great danger and in great expenditure.
A further presentation relating to this known airborne platform (CTV), entitled “Measurement at the Air Sea Interface with the Controlled Towed Vehicle” was given by G. Kok, President of Droplet Measurement Technologies (DMT) before the American Meteorological Society at the 20th Symposium on Boundary Layers and Turbulence, or on the 18th Conference on Air-Sea Interaction on Monday 9 Jul. 2012 in Westin Copley Place, Boston, Mass., USA, published under the following URL (downloadable from the internet, status Nov. 11, 2013) <<https://ams.confex.com/ams/20BLT18AirSea/webprogram/Paper209425.html.>>.
However, the disclosure content of this publication does not go beyond that of the first-mentioned publication. The same applies to a flyer 11/12/11 Rev A issued by Droplet Measurement Technologies (DMT) relating to the CTV, which flyer was handed out to the inventors by G. Kok on the occasion of a conference by the American Geophysical Union AGU in San Francisco, USA, 5-9 Dec. 2011.
A malfunction system for the control system of an aircraft is, for example, known from EP 1 422 680 B1. In this arrangement, in the case of an emergency, the central control of selected systems can be overruled and the aircraft can be moved to a final approach alignment. Moreover, generally-speaking, from EP 2 617 647 A2 an actuator system for use with actuators, for example in aviation, is known, which actuator system in the case of an emergency in the deactivated state assumes a defined state and locks it there so that this state is maintained even in the case of unintended or incorrect control. The system is reversibly switchable, by way of various kinematic elements, between the locked position (first dead-centre position) and an unlocked position (second dead-centre position), wherein it can, however, also be moved beyond the dead-centre positions. Consequently no reliable locking is ensured. Finally, from U.S. Pat. No. 6,111,327 A a malfunction module is known which in the case of an impact switches off the electrical power to a vehicle. To this effect said module comprises a spring-loaded blade lever that toggles a switch.